The concentration of elements such as carbon and nitrogen in plants is

• A
  Above $10 \text{ mmol } kg^{-1}$ of dry matter
• B
  Less than $10 \text{ mmol } kg^{-1}$ of dry matter
• C
  Equal to $10 \text{ mmol } kg^{-1}$ of dry matter
• D
  Between $1-10 \text{ mmol } kg^{-1}$ of dry matter